Spin turbulence in spinor Bose-Einstein condensates

Makoto Tsubota,Kazuya Fujimoto

doi:10.1088/1742-6596/497/1/012002

Abstract

We summarize the recent theoretical and numerical works on spin turbulence (ST) in spin-1 spinor Bose-Einstein condensates. When the system is excited from the ground state, it goes through hydrodynamic instability to ST in which the spin density vector has various disordered direction. The properties of ST depend on whether the spin-dependent interaction is ferromagnetic or antiferromagnetic. ST has some characteristics different from other kinds of turbulence in quantum fluids. Firstly, the spectrum of the spin-dependent interaction energy exhibits the characteristic power law different from the usual Kolmogorov -5/3 law. Secondly, ST can show the spin-glass-like behavior; the spin density vectors are spatially random but temporally frozen.

Highlights

Quantum turbulence (QT) is currently one of the most important topics in low temperature physics [1]
Spinor Bose-Einstein condensates propose a novel system of turbulence in quantum fluids, namely spin turbulence (ST) in which the spin density vectors are disordered
When the dynamics starts from an initial state with the energy much higher than the ground state or the system is excited from the ground state by an applied field, ST appears after hydrodynamic instability

Summary

INTRODUCTION

Quantum turbulence (QT) is currently one of the most important topics in low temperature physics [1]. We have studied theoretically and numerically spin turbulence (ST) in spinor BECs [19,20,21,22,23,24]. In contrast to the two-component BECs, interatomic interactions allow for a coherent transfer of population between different hyperfine spin states (spinexchange collisions), which yields a fascinating physics different from two-component BECs. Spinor BECs can be another important stage of turbulence in quantum fluids. When the system is highly excited from the ground state, it goes through hydrodynamic instability to ST in which the spin density vector has various disordered direction This ST shows characteristic behaviors different from other kinds of QT. The spin density vectors are spatially random but temporally frozen, which reminds us of the analogy of spin glass [22] This article reviews such recent works on ST

THE GROSS-PITAEVSKII EQUATIONS AND THE HYDRODYNAMIC DESCRIPTION

SPIN TURBULENCE WITH THE FERROMAGNETIC INTERACTION

Spin turbulence and the energy spectrum

Spin-glass-like behavior

SPIN TURBULENCE WITH THE SMALL SPIN MAGNITUDE

CONCLUSIONS AND DISCUSSIONS